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arXiv · 2604.03204

Revisiting the Rhoades-Ruffini bound

David Blaschke·Adrian Wojcik
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Abstract

We revisit the derivation of the Rhoades-Ruffini bound on the upper limit for the maximum mass of neutron stars and find that the assumption made there for the onset of an ultimately stiff phase of high-density matter is not stringent. Relaxing this assumption and allowing for an onset of stiff non-nucleonic matter under neutron star constraints at the saturation density or below boost the upper limit of the theoretically possible maximum mass to $4~M_\odot$ or higher, in the mass-gap region between neutron stars and stellar-mass black holes. We provide a fit formula for the dependence of this upper limit on the speed of sound and the onset density of the deconfinement transition.

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David Blaschke, Adrian Wojcik. 2026-04-03. Revisiting the Rhoades-Ruffini bound. https://arxiv.org/abs/2604.03204

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